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Next Generation Nuclear Plant: A Report to Congress

The U.S. Department of Energy’s (DOE’s) Next Generation Nuclear Plant (NGNP) project helps address the President’s goals for reducing greenhouse gas emissions and enhancing energy security. The NGNP project was formally established by the Energy Policy Act of 2005 (EPAct 2005), designated as Public Law 109-58, 42 USC 16021, to demonstrate the generation of electricity and/or hydrogen with a high-temperature nuclear energy source. The project is being executed in collaboration with industry, DOE national laboratories, and U.S. universities. The U.S. Nuclear Regulatory Commission (NRC) is responsible for licensing and regulatory oversight of the demonstration nuclear reactor.

The NGNP project includes design, licensing, construction, and research and development (R&D) conducted in two phases as defined in EPAct 2005. Phase 1 consists of pre-conceptual and conceptual design and demonstration activities leading to the selection of a single technology for NGNP. Phase 2 is the preliminary and final design leading to licensing and construction of a demonstration plant. Licensing scope supports the development of a licensing framework for high-temperature gas reactors and includes the preparation and submission of a combined construction and operating license application (COLA) for the NGNP. The scope of R&D falls into the following four major technical areas: (a) fuel development and qualification, (b) graphite qualification, (c) high-temperature materials qualification, and (d) design and safety methods validation. Licensing and R&D activities are included in both Phase 1 and Phase 2 of the project, with appropriate risk-mitigation strategies incorporated to minimize the impact on design from conducting research and development in parallel.

From fiscal year (FY) 2006 through FY 2010, a total of $528.4 million has been appropriated for the NGNP project. Of this amount, $192.8 million will have been spent on NGNP research and development; $177.6 million on NGNP design, engineering, licensing and project management; and $158 million on university R&D programs and other NGNP-related activities.

On September 18, 2009, DOE published a funding opportunity announcement (FOA) for the conceptual design and demonstration activities of the NGNP. Proposals were received by the Department on November 16, 2009 and winning proposals were announced in March. Conceptual design reports are expected to be completed by September 30, 2010. These conceptual design reports are the last major deliverables of Phase 1 of the NGNP project.

DOE plans to have the Nuclear Energy Advisory Committee launch a programmatic review of the NGNP project in September 2010. This review will inform the Secretary of Energy on the readiness of the NGNP project to proceed to Phase 2. It is expected that a Secretarial decision on whether or not to proceed into Phase 2 will be made in January 2011. All planned milestones and activities referenced in this report that occur after that timeframe are dependent on the outcome of the Secretarial decision. Phase 2 includes the competitive selection of a single reactor design for demonstration as the NGNP. The conceptual design reports completed in Phase 1 would inform the competitive selection of a final design for the prototype reactor and plant.

Phase 2 also includes finalizing the design of all safety systems in order to facilitate the preparation and submittal of a COLA to the NRC in accordance with the licensing strategy recommended in the NGNP Licensing Strategy Report to Congress (2008). The COLA is presently scheduled for submittal in FY 2013. The COLA schedule will be re-evaluated in conjunction with the conceptual design activities in preparation for the Secretarial decision and revised as necessary. Whether or not the overall schedule for completing the construction of the NGNP in FY 2021 can still be met depends on many factors, including funding availability from both federal and private sectors.

Assuming completion by FY 2021, the current preliminary project cost estimate, based on FY 2007 pre-conceptual design information, is $4 billion. Improved cost estimates will be part of the conceptual design reports due in September 2010. More detailed cost estimates that would meet commercial financing requirements are dependent on the completion of preliminary design activities. The relative share of costs allocated to government and industry will conform to EPAct 2005 requirements. To date, cost share requirements have not been imposed on the national laboratories and universities who have been conducting R&D on enabling gas reactor technologies. After a public-private partnership is formed for Phase 2 activities, any R&D required to support a specific reactor design may be cost shared in accordance with EPAct 2005.

Currently there are two major types of high-temperature gas reactor designs under consideration: the pebble bed and the prismatic designs. Early versions of these reactor designs were demonstrated in the 1970s and 1980s. Test reactors for the pebble bed and prismatic designs are presently operating in China and Japan respectively. Both of these reactor designs are graphite- moderated and helium-cooled, and both use coated particle fuel kernels embedded in a graphitic matrix material. The primary differences between these designs are the shape of the fuel-bearing graphitic matrix and the distribution of fuel in the reactor core.

The pebble bed design uses hundreds of thousands of tennis ball-sized spherical fuel elements called pebbles. The pebbles are stacked together in contact with each other like gumballs in a vending machine. The pebbles are added at the top, circulate through the reactor core, and are removed from the bottom. Fuel replacement in a pebble bed design is continuous and allows for online refueling.

The prismatic design uses cylindrical fuel elements that are pressed into channels drilled into graphite blocks. These fuel-bearing blocks are stacked in columns in fixed locations in the reactor core. Refueling is accomplished by shutting down the reactor, removing the fuel-bearing blocks, and replacing the oldest ones with new blocks.

Most of the challenges for these two reactor types are held in common. These consist of licensing and regulatory issues associated with containment and emergency planning, business issues associated with breaking into new markets for nuclear energy in the transportation and industrial sectors, and infrastructure issues associated with first-of-a-kind technology demonstrations. Other challenges are unique to each reactor type. For the pebble-bed, the stochastic nature of the fuel presents a unique design and licensing challenge. For the prismatic design, controlling coolant flow through the narrow channels of the graphite blocks is a unique design and manufacturing challenge.